9, 10, 11. One significant factor will be where you want to carry the weight. Generally, the style for touring bikes lately has been to put panniers in the rear, which is fine. But there are bikes that have been designed to carry the weight in the front, based on the French randonneur tradition. These were bikes also designed for long loaded rides and framebuilders are recognizing their value again.
Another thing to consider is having the bike built for a specific fender, so that the mounts or the fender itself is an integral part of the bike. If I was doing that, I would use the Gilles Berthoud stainless steel fenders. They are very impressive, sturdy, and well-designed.
Also, if a rear rack is a must (or front, too) than you may want to consider having it built for the frame, depending on your budget. That will be another place to save weight instead of worrying about frame materials; having these things be designed into the frame. It also means you will never have to worry about customizing a fender or rack to your frame, and if you choose your bags ahead of time, that could be a very smart and holistic approach to this project.